1. Field of the Invention
The present invention relates to an improved process for the separation of propylene glycol and propylene glycol ethers from aqueous streams containing these materials.
2. Description of the Prior Art
A great deal of work has been done to develop improved processes for the production of propylene oxide. Such processes include direct oxidation processes whereby a mixture of propylene, oxygen and hydrogen are reacted in the presence of appropriate catalyst to form propylene oxide. See, for example, U.S. Pat. Nos. 6,710,192, 6,063,942, 6,281,369, 6,005,123 and the like.
In such procedures, large waste water streams are generated which contain propylene glycol and propylene glycol ethers, usually in minor amounts. Separation of the propylene glycol and ethers by distillation procedures is possible but quite costly since evaporation of substantially all of the water is required.
The development of new and improved procedures for the separation of propylene glycols and lower alkyl ethers thereof is an important objective.